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    <title>ShellCheck: SC3052 – In POSIX sh, arithmetic base conversion is undefined</title>
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    <h1>SC3052 – ShellCheck Wiki</h1>
    <a href="https://github.com/koalaman/shellcheck/wiki/SC3052">See this page on GitHub</a>
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    <h2 id="in-posix-sh-arithmetic-base-conversion-is-undefined">In POSIX
sh, arithmetic base conversion is undefined</h2>
<h3 id="problematic-code">Problematic code:</h3>
<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="SC3052.html#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="co">#!/bin/sh</span></span>
<span id="cb1-2"><a href="SC3052.html#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="bu">echo</span> <span class="st">&quot;Hex </span><span class="va">$1</span><span class="st"> is decimal </span><span class="va">$((</span><span class="dt">16#</span><span class="va">$1))</span><span class="st">&quot;</span></span></code></pre></div>
<h3 id="correct-code">Correct code:</h3>
<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="SC3052.html#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="co">#!/bin/sh</span></span>
<span id="cb2-2"><a href="SC3052.html#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="bu">echo</span> <span class="st">&quot;Hex </span><span class="va">$1</span><span class="st"> is decimal </span><span class="va">$(</span><span class="bu">echo</span> <span class="st">&quot;ibase=16; </span><span class="va">$1</span><span class="st">&quot;</span> <span class="kw">|</span> <span class="fu">bc</span><span class="va">)</span><span class="st">&quot;</span></span></code></pre></div>
<h3 id="rationale">Rationale:</h3>
<p>Your script uses a shell feature not supported by the shebang. Either
rewrite the script to be portable, or change the shebang to explicitly
require a shell like Bash.</p>
<p>In this case, using radix specifiers in arithmetic contexts, such as
<code>$((16#DEADBEEF))</code> is not portable. <code>bc</code>
ibase/obase can be used instead.</p>
<h3 id="exceptions">Exceptions:</h3>
<p>None</p>
<h3 id="related-resources">Related resources:</h3>
<ul>
<li>Help by adding links to BashFAQ, StackOverflow, man pages, POSIX,
etc!</li>
</ul>
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    <p style='font-size: 80%'><a href="../index.html">ShellCheck</a> is a static analysis tool for shell scripts. This page is part of its documentation.</p>
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